Core B will provide a facility for novel optical instrumentation to the investigators of this Program Project. The Core's primary functions will be to assist in experiments that require expertise and specialized equipment not available in the individual sub-project laboratories and to develop state of art optical instrumentation. The Specific Aims of the Core are to: (1) provide guidance and expert help to the members of the Program Project in using (a) optical trapping to measure force, displacement, and kinetics of motors and adhesion properties of bimolecular interactions, and Total Internal Reflection Microscopy (TIRF), FIONA and other single-molecule fluorescence techniques; and (2) develop (a) combined optical trap-TIRF spectroscopy, (b) methods for measurement of motor stiffness from variance and covariance if single molecule data traces, and (c) techniques for the creation of higher-order motor cytoskeletal assemblies.